In diagnostic imaging systems, it is desirable to maximize resolution, signal to noise ratio and the relative intensity contrast between different materials through which the radiation passes, i.e. bone, soft tissue, contrast material, gas, etc. Scientists in the field are continuously attempting to improve resolution, lower the noise and increase the contrast to improve the quality of the pictures obtained.
In digital fluorography, the person conducting the study generally learns by experience where to set the various controls on the system. For example, if the person conducting the study wants to image an object that has small changes in relative opaqueness then, the voltage output of the X-ray power supply is set high to provide the requisite photon energy level. Other controls generally are available to the clinician. For example, controls are available for changing the X-ray tube current, when the power supply provides energy in a continuous mode. If energy is supplied in a pulsed mode then the length of the pulse or the number of pulses used per image can be varied. Also, the number of optical photons is controlled by varying the iris or the shutter opening in the optical system. Other functions of DF signals such as those described in the patent application entitled "Improved Digital Fluorography", bearing Ser. No. 546177, filed, in the United States on Oct. 27, 1983, now U.S. Pat. No. 4,555,728, which is assigned to the assignee of this application are controlled by the analog-to-digital converter circuitry.
A problem with these imaging systems is that a variation in one of the parameters has an effect on at least certain of the other parameters. Thus when one parameter is set to a desired value the adjustment of another parameter will change the first adjusted parameter. Accordingly, there is a real need for a system that automatically adjusts at least certain of the parameters necessary to obtain high quality images.